The Footprint Blog

Solar power gets thirsty

I’d love to believe that all renewable energy projects are a great way to generate power without putting a strain on our resources and the planet. Unfortunately, many projects present uncomfortable tradeoffs. The New York Times’ greeninc blog reported recently that utility-scale solar power projects can be incredibly water intensive.

Solar power projects are all about concentrating the energy of the sun, which is, well, hot. The problem is most machinery doesn’t have a limitless tolerance for heat and so must be cooled down. In one common, simple technology called “wet-cooling”, solar thermal projects are cooled with running water. The two projects mentioned in the Times article will use more than a billion gallons of water every year. While this isn’t anywhere near the volumes of water used for agriculture, it’s not a drop in the bucket either: look at the specifics of one particular project.

NextEra Energy Resources, a subsidiary of the utility FPL Group, is developing the Genesis project in the Chuckwalla Valley in the Californian Sonoran Desert. This project. combined with a similar one nearby, would tap about 5 percent of the valley’s available water.

Five percent of the water resources of the local ecosystem is significant, even for an undeveloped desert environment. I’m not saying I’m opposed to solar, but rather that it’s important that we look at all the impacts of these projects and consider other options. In this case “dry cooling” technology uses significantly less water (but costs significantly more). As these projects progress through California’s permitting process, it will be interesting to see how decision makers balance these tradeoffs. It’s a great reminder that no renewable energy project is a silver bullet and that it will take a mix of technologies to address our growing energy demands responsibly.

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